Federal Republic of Germany Priority Application 101 46 346.4, filed Sep. 20, 2001 including the specification, drawings, claims and abstract, is incorporated herein by reference in its entirety.
The invention relates to a coolant circuit for a motor vehicle having an engine that is cooled with an engine coolant.
DE 198 47 607 A1 discloses a heating circuit for a motor vehicle, in which a supply heater for the heating circuit is provided. The exhaust gases of the engine are fed into an exhaust system upstream or downstream of a catalytic converter.
DE 31 03 198 A1 discloses a heat exchanger which is arranged in an exhaust system and which makes additional heating capacity available.
WO 97/47865 relates to a heat exchanger for the exhaust gas recirculation line that can be integrated into the coolant circuit, so that, even with the heating device switched off, the heat absorbed from the recirculated exhaust gas heats up the coolant, in order to achieve a cooling of the recirculated exhaust gas even when the heating is not in use. In this case, the heat exchanger may also be incorporated directly into the heating circuit if the coolant flows constantly through the heat exchanger. As a result of the cooling of the exhaust gas by the heat exchanger, a lowering of the combustion peak temperature and a reduction in the NOx emissions occur.
However, coolant circuits of this type still leave much to be desired.
One object of the present invention is to provide an improved coolant circuit of the type discussed above.
Another object of the invention is to provide an improved method of cooling the exhaust gases from an engine in a motor vehicle.
A further object resides in providing an improved motor vehicle containing the improved cooling circuit according to the invention.
In accordance with one aspect of the present invention, there has been provided a coolant circuit for a motor vehicle having an engine that is cooled with an engine coolant, comprising: a radiator for cooling the engine coolant; an exhaust gas heat exchanger; and a passageway for supplying engine coolant from the radiator directly to the exhaust gas heat exchanger.
In accordance with another aspect of the invention, there is provided a method of controlling the temperature of exhaust gas supplied to a catalytic converter from an engine in a motor vehicle that includes an engine coolant circuit and a radiator in the engine coolant circuit, comprising exchanging heat between the exhaust gas and the engine coolant in a heat exchanger; and supplying engine coolant directly to the heat exchanger from the radiator.
In accordance with yet another aspect of the invention, there is provided a motor vehicle having an engine that is cooled with an engine coolant by means of a coolant circuit, wherein the coolant circuit comprises a coolant circuit as described above.
In an alternative aspect of the present invention, there is provided a coolant circuit for a motor vehicle having an engine that is cooled with an engine coolant, comprising: a radiator for cooling the engine coolant; an exhaust gas heat exchanger; a passageway for supplying engine coolant to the exhaust gas heat exchanger; and a control system for controlling the temperature of engine coolant supplied to the exhaust gas heat exchanger, comprising an arrangement for selectively feeding engine coolant directly from the radiator into the passageway.
According to still another aspect of the invention, there has been provided a method of utilizing exhaust gas heat from an engine in a motor vehicle to heat an internal compartment of the vehicle that includes an engine coolant circuit and a radiator in the engine coolant circuit, comprising: exchanging heat between the exhaust gas and the engine coolant in a first heat exchanger; supplying engine coolant directly to the heat exchanger from the radiator; and exchanging heat between the engine coolant downstream of the exhaust gas heat exchanger and air being fed into the internal vehicle compartment in a second heat exchanger.
Further objects, features and advantages of the present invention will become apparent from the detailed description of preferred embodiments that follows, when considered together with the accompanying drawings.